A work machine, such as a hydraulic excavator, is known in which a hydraulic pump is driven by the power of an engine and the hydraulic fluid discharged from the hydraulic pump is used to drive hydraulic actuators. Generally, in such work machines, the operator operates the EC dial to determine an engine speed and operates operation levers to determine the speed and power of each hydraulic actuator.
For example, there is a work machine with a heavy load work mode, a normal work mode, and an economy mode for saving fuel (see FIG. 5 of Patent Document 1). In the work machine, the engine speed can be set to any value between the minimum speed and the maximum speed determined for each mode by the EC dial.
There is also a work machine in which the EC dial is used to determine a target engine speed, the engine is controlled such that its speed reaches the target engine speed, and the hydraulic pump is controlled such that the pump absorption torque corresponding to the engine speed is achieved. This EC dial can instruct any target speed, and the pump absorption torque is adjusted accordingly to any value desired (see, for example, FIG. 6 of Patent Document 2).
There is another work machine that determines the target engine speed to any speed excluding a preset speed range for the purpose of preventing resonance resulting from particular engine speeds (see FIGS. 4 and 5 of Patent Document 3).